Why CT Secondary Should Not Kept Open In Tamil

CT Secondary not In Open Circuit In Tamil.
Basically, a Current Transformer is a step up transformer.
Where on the secondary side, current is decreased and Voltage is increased.
A current transformer should never be open-circuited while main current is passing through the primary winding.
If the load is removed from the secondary winding while the main circuit current is flowing, most of the primary winding current becomes magnetizing current.
But the vector angles change in such a way as to keep the total current in the primary the same as before.
Because the main circuit is now mostly magnetizing current, the flux in the core shoots up to a high level and a very high voltage appears across the secondary.
Due to the high turn ratio usually found in these transformers, the voltage in this condition can reach a dangerously high level, which can break down the insulation.
It also becomes a hazard to personnel.
The high flux can saturate the core and result in strong residual magnetism left in the core, thereby increasing magnetization current and introducing error in the transformation ratio.
One has to put a short the secondary winding to operate a Current Transformer.
More: www.electrical...
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